Marstek Venus E 3.0
A capable 5.12 kWh AC-coupled battery from Europe's balcony solar boom, but not yet sold or certified in the US as a self-install plug-in kit.
Characteristics
- Capacity: 5120 Wh LiFePO4, expandable to 15.36 kWh
- Backup output: 2.5 kW continuous during an outage
- Install: AC-coupled behind an existing grid-tied inverter
- US status: No confirmed UL3700 certification as of 2026
- Best used today as a backup add-on, not a solo plug-in kit
Detailed overview: Marstek Venus E 3.0 AC-coupled battery, US availability
The Marstek Venus E 3.0 is an AC-coupled home battery designed for households that already have solar panels and an inverter. Rather than replacing anything, it plugs in downstream of an existing photovoltaic system to store surplus power, with no rewiring of the existing installation. In Europe, where it ships with a 230V/50Hz on-grid mode, it has built a strong track record in Europe's balcony solar market.
Its 5120 Wh LiFePO4 pack is rated for over 6000 cycles at 90% depth of discharge, and up to three units can be combined for 15.36 kWh. A dedicated backup output delivers up to 2.5 kW continuously during a power outage, enough for lighting, a router or a fridge, a function that does not depend on exporting power to the grid.
For the US specifically, our research found a real gap between the product and the market. Marstek's own marketing already states that pushing its full 800W on-grid output requires local utility or government approval, a materially different position from Utah-cleared plug-in products. We found no UL3700 certification, the standard now used to certify plug-in battery equipment for the US, for the Venus E. Marstek's English-language storefront (marstekenergy.com/en-us) still prices the unit in euros rather than dollars, and its dedicated Where to Buy page for that locale was, at the time of writing, a placeholder reading the page is coming soon. No listing was found on Amazon.com either; the handful of resellers that ship the Venus E to US buyers are based in Europe.
None of this rules out a Venus E in a US home. It means the realistic route today is through a licensed solar installer, adding it behind an already grid-tied, permitted system, and leaning on its backup port rather than treating it as an off-the-shelf, self-install plug-in purchase. Readers specifically looking for a Utah-legal, self-install plug-in battery should compare it against EcoFlow's Stream Ultra, which currently has that certification and marketing in place.
Full specifications
Detailed characteristics
Battery
| Technology?Battery chemistry; LiFePO4 lasts far longer and can be fully discharged, gel/AGM is maintenance-free and cheaper. | LiFePO4 (lithium) |
|---|---|
| Nominal voltage?Battery voltage (12, 24 or 48 V). | 51.2 V |
| Capacity?Capacity in amp-hours; multiply by voltage to get energy in Wh. | 100 Ah |
| Energy?Stored energy in watt-hours. | 5120 Wh |
| Delivered energy, measured?Energy that actually leaves the battery and reaches the devices. Always below the stored energy, as conversion costs heat. Taken from our in-depth review. | 4483 Wh |
| Cycle life?Rated number of charge/discharge cycles, at the stated depth of discharge. | 6000 cycles (90 %) |
Power and protection
| Output power?Maximum power delivered (for storages with a 230 V output). | 2500 W |
|---|---|
| Built-in BMS?Battery management system protecting against overcharge, deep discharge, short-circuit and overcurrent (lithium batteries). | Yes |
| Low-temperature protection / heating?Cuts off or heats charging in cold weather to protect the lithium cells. | Yes |
Solar section
| Micro-inverter?Power of the inverter that feeds energy back into the home grid. | 2500 W |
|---|
Connectivity
| Bluetooth?Monitoring and settings via an app over Bluetooth. | Yes |
|---|---|
| Wi-Fi?Remote control and updates over Wi-Fi. | Yes |
Durability and format
| Ingress protection?Water and dust resistance (IP rating). | IP65 |
|---|---|
| Maintenance-free?Sealed battery needing no water top-up (gel / AGM). | Yes |
| Weight?Weight of the battery. | 132.3 lb (60 kg) |
| Dimensions (L × W × H)?Length × width × height, in millimetres. | 18.9 × 6 × 24.6 in (480 × 153 × 624 mm) |
Availability and warranty
| Market launch?Date the model first became available on the European market. Useful to place its generation: technology moves fast in this segment, and a device several years old may be at the end of its commercial life. | August 2025 |
|---|---|
| Warranty?Length of the manufacturer's warranty. | 10 years |
Related video
Video: Marstek Venus-E GEN 3.0 - Brandaktueller Energiespeicher im Test! - Published on 26/08/2025
Our tester's review: Julien De Jurquet
On the strength of the hardware alone, the Venus E 3.0 deserves its European reputation: a genuinely simple AC-coupled battery that adds real backup capacity behind an existing solar setup. But this review is about buying one in the US today, and there our enthusiasm cools. We could not find it listed on Amazon.com, and Marstek's own English-language US page still displays its price in euros, with a Where to Buy page that literally reads coming soon. No UL3700 certification turned up in our research either, the standard now used to clear plug-in battery products in the US. Marstek's own site is upfront that pushing the full 800 W of on-grid output requires local utility or government approval, a different proposition from EcoFlow's Utah-cleared, no-approval devices. None of this means the hardware is unsafe or unusable. It means the realistic US path today runs through a licensed installer, adding it behind an existing interconnected system for its 2.5 kW backup output, not ordering it online expecting a Utah-style wall-outlet install.
In-depth review Marstek Venus E 3.0: Our Full Review 3.6/5 Read our full review → Efficiency 3.7 Portability and size not measured Weather resistance not measured Output ports not measured Capacity and expansion 4.0 Solar input and MPPT not measured Control and smart features 2.7 Installation and compliance 3.9 Build and endurance 3.9 Battery compatibility not measured Safety and protections not measuredFrequently asked questions: Marstek Venus E 3.0 AC-coupled battery, US availability
Not easily as of this research. It is not listed on Amazon.com, and Marstek's own US-facing product page still shows euro pricing with a Where to Buy page marked coming soon. A handful of European resellers will ship it, but there is no established US storefront.
This is not clearly established. Marstek's own marketing states that its 800W on-grid output requires local utility or government approval, and we found no UL3700 certification for it, the standard now used to clear plug-in battery products in the US.
Its most defensible US use is as a backup battery, added by a licensed installer behind an existing grid-tied, permitted solar system, drawing on its 2.5 kW backup output during outages rather than as a stand-alone plug-in purchase.
EcoFlow's Stream Ultra currently has US marketing and self-install positioning tied to Utah's HB 340 law. The Venus E 3.0 has no equivalent US certification or retail presence confirmed as of this research, despite similar hardware ambitions.
Yes. It is an AC-coupled battery, not a complete solar kit: it has no built-in MPPT solar input, and is designed to add storage behind a photovoltaic system that already has its own inverter.
Need help choosing?
Other products in the "Plug and play solar batteries" category
Allpowers BS2500 Pro
$1599.00
A capable 2600Wh plug-and-play balcony battery that has done well in Europe, but not yet sold through a US store or Amazon.com as of 2026.
Anker Solix Solarbank 2 E1600 AC
$946.45 (7)
1.6 kWh of AC-coupled solar storage for your balcony: built-in 800W microinverter, dual MPPT, IP65 rating and a capacity expandable up to 9.6 kWh.
Anker Solix Solarbank 3 E2700 Pro
$1214.40 (7)
2688Wh of plug-and-play solar storage: 4 MPPT, a bidirectional 1200W microinverter and an AI that optimises your self-consumption on its own. Balcony solar finally pays off.
Anker Solix Solarbank 4 E5000 Pro
$2300.45
5 kWh of solar storage for your balcony: 4 MPPT, a bidirectional PluginPower 2.0 inverter, IP66 rating and a capacity expandable to 30 kWh.
Published on 02/09/2026